Effect of Different Types of Toothpaste on the Frictional Resistance Between Orthodontic Stainless Steel Brackets and Wires

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1 Original Article Effect of Different Types of Toothpaste on the Frictional Resistance Between Orthodontic Stainless Steel Brackets and Wires Tahereh Hosseinzadeh Nik 1, Tabassom Hooshmand 2, Homa Farhadifard 3 1 Professor, Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran; Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 2 Associate Professor, Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran; Department of Dental Biomaterials, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 3 Assistant Professor, Department of Orthodontics, School of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran Corresponding author: H. Farhadifard, Department of Orthodontics, School of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran homa.far1989@gmail.com Received: 25 June 2017 Accepted: 16 August 2017 Abstract Objectives: The purpose of this study was to investigate the effect of different types of toothpaste on the frictional resistance between stainless steel brackets and archwires. Materials and Methods: Ninety stainless steel orthodontic brackets with stainless steel wires were bonded to bovine teeth and were divided into 6 groups for application of the following toothpastes: Colgate Total Advanced Whitening, Colgate Total Pro Gum Health, Colgate Anticavity, Ortho.Kin, and Sunstar GUM Ortho toothpastes. No toothpaste was applied in the control group. Each group was brushed by a brushing machine with the use of the designated solution for 4.5 minutes. The frictional force was measured in a universal testing machine with a crosshead speed of 10 mm/minute over a 5-mm archwire. Data were analyzed using one-way analysis of variance (ANOVA) at the 0.05 significance level. Results: The frictional resistance values of Ortho.Kin and GUM Ortho toothpastes and the control group were not significantly different (P>0.05). However, there were significant differences between the frictional resistance values of Colgate Total Pro Gum Health and Colgate Anticavity toothpastes with that of the control group (P<0.05). The highest and lowest frictional resistance values were related to Colgate Total Pro Gum Health toothpaste and the control group, respectively. Conclusions: Among the evaluated toothpastes, the orthodontic toothpastes did not increase the frictional resistance between the orthodontic stainless steel brackets and wires. Key words: Orthodontic Brackets; Orthodontic Wires; Friction; Toothpastes; Stainless Steel Journal of Dentistry, Tehran University of Medical Sciences, Tehran, Iran (2017; Vol. 14, No. 5) INTRODUCTION One of the most important elements of a successful orthodontic treatment is the control of dental caries and maintenance of a good oral hygiene [1]. Fluoridecontaining commercial mouth rinses, toothpastes, and prophylactic gels are widely used to prevent dental decay and to relieve dental sensitivity in the oral cavity [2]. Regular tooth brushing removes dental stains and keeps the teeth clean. The whitening ingredients in toothpastes include chemical chelants, oxidizing agents, and particulate abrasives. Currently, the abrasives frequently used in toothpastes include precipitated silica, calcium carbonate, alumina, and a variety of calcium phosphates [3]. Myriad commercially-available dentifrices with miscellaneous ingredients are commonly used by orthodontic patients. Some of these ingredients can induce alterations in proximity to metal. These changes on the surface properties of orthodontic brackets may negatively affect the orthodontic procedure [4] September 2017; Vol.14, No. 5

2 J Dent (Tehran) Fig. 1: V-8 cross brushing machine The orthodontic sliding mechanics, a technique used for closing the dental spaces, is usually performed by moving the brackets along the archwire or by sliding the wire through the brackets and molar tubes. The friction caused by the contact between the bracket and archwire is the main disadvantage affecting the sliding mechanics [5]. Friction is the force that delays or stops the movement of two materials in contact, and its direction is tangential to the common interface of the two surfaces [6,7]. Friction can stop the movement of the tooth to which the bracket is attached, can decrease the available force by almost 40% and may cause anchorage loss [8]. The factors that influence the friction consist of the ligation type, applied force, bracket-wire clearance, wire size and morphology, bracket dimensions, torque at the bracket-wire interface, type of movement at the bracket-wire interface, and type of bracket and wire [9]. Several studies have investigated the effects of different mouthwashes such as chlorhexidine and fluoride on the frictional resistance between orthodontic brackets and wires [5, 10-12]. Kao et al [9] immersed metal brackets and various types of orthodontic wires in the acidified phosphate fluoride (APF) prophylactic solution and investigated the frictional resistance rate. It was shown that the static frictional resistance of stainless steel, heat-activated nickel-titanium (Ni-Ti), and beta-titanium (B-Ti) alloy wires immersed in 0.2% APF solution was significantly higher than that of Hosseinzadeh Nik et al the wires immersed in artificial saliva [9]. Hosseinzadeh Nik et al [5] evaluated the impact of 0.2% chlorhexidine mouthwash on the surface roughness and frictional resistance between orthodontic brackets and archwires. They reported that a 1.5-hour immersion in this prophylactic agent did not have any significant influence on the archwires' surface roughness or on the frictional resistance between stainless steel orthodontic brackets and stainless steel or Ni-Ti archwires. Special toothpastes have been introduced to the market, specifically designed for orthodontic treatment, which can impose variable effects on orthodontic brackets and wires. Kinoshita et al [13] investigated the impact of whitening toothpastes on the surface roughness of nanofiller-based composites. They used Colgate Luminous White, Oral-B 3D White and Close- Up Diamond Attraction as whitening toothpastes, and Colgate Total 12 toothpaste as the control group. It was concluded that the whitening toothpastes could increase the surface roughness of the composites [13]. Barbieri et al [14] studied the influence of whitening dentifrices (Colgate Max White and Close-Up Extra Whitening) compared to a nonwhitening dentifrice (Colgate Total 12) on the surface roughness of commercial composites and reported that the whitening toothpastes caused higher surface roughness in the composites compared to the non-whitening type. The effect of different types of toothpaste on the frictional resistance of orthodontic appliances has not been previously investigated. Therefore, the purpose of this study was to explore the effect of different types of toothpaste on the frictional resistance between stainless steel brackets and archwires. MATERIALS AND METHODS Ninety upper central stainless-steel metal brackets (standard edgewise, Dentsply GAC International, Islandia, NY, USA) with inch slot size were selected inch standard September 2017; Vol.14, No. 5

3 Hosseinzadeh Nik et al Frictional Resistance of Orthodontic Brackets and Wires by Toothpastes Fig. 2: Friction testing apparatus rectangular straight stainless-steel orthodontic wires (Dentsply GAC International, Islandia, NY, USA) that were cut into 8-cm pieces were used. The brackets and wires were cleaned with alcohol wipes and were observed under a stereomicroscope (Olympus, Tokyo, Japan) in order to eliminate the specimens with manufacturing defects. Bovine maxillary central incisors were collected and cleaned by immersion in 0.05% Chloramine-T solution for 7 days. The brackets were then bonded to the bovine teeth, and the orthodontic wires were tied to them using an elastomeric module (O-ring, Dentaurum intraoral elastics, Dentaurum GmbH Co., Ispringen, Germany). Next, the specimens were randomly divided into six groups for toothpaste application (n=15): 1) Colgate Total Advanced Whitening toothpaste 2) Colgate Total Pro Gum Health toothpaste 3) Colgate Anticavity toothpaste 4) Ortho.Kin toothpaste 5) Sunstar GUM Ortho toothpaste 6) No toothpaste as control The specifications of the toothpastes are provided in Table 1. V-8 cross brushing machine (Fig.1, Oaj Andish Spadan Co., Isfahan, Iran) was used for brushing the teeth according to the ISO 11609:2017 standard [15]. A solution containing 25g toothpaste, 20cc of modified Fusayama artificial saliva with the ph of 6.75 containing NaCl (400mg/l), KCl (400mg/l), CaCl2 H2O (795mg/l), NaH2PO4 2H2O (690mg/l), Na2S 9H2O (5mg/l), Urea (1000mg/l), and 20cc of distilled water was used in each experimental group. Also, a solution containing 20cc of modified Fusayama artificial saliva and 20cc of distilled water (with no toothpaste) was used in the control group [3]. Each tooth was brushed in 65cc of its designated solution at the 150-cycle/minute frequency for 4.5 minutes (an equivalent of one month of tooth brushing of each dental surface for 3 times per day). Next, each tooth was rinsed with 20cc of distilled water for 20 seconds, and in order to avoid bracket distortion, the brackets were separated from the teeth using a bur mounted on a handpiece (the brackets and wires were covered with a sterile gauze in this stage). The frictional force was measured using a universal testing machine (Zwick/Roell Z050, Germany). A custom-made fixture was designed for holding the wires as shown in Figure 2. A plumb line was suspended in order to ensure that the bracket mount was parallel to the vertical line scribed on the steel bar base of the bracket mount set. The load measuring cell was calibrated between 0 and 5 N, and a 5-mm section of the archwire was driven through the bracket at a crosshead speed of 10 mm/minute. Note that no torsion must be generated in the specimen during clamping. The static friction was recorded as the maximum frictional force needed to initiate the movement of the bracket over the 5-mm test distance. The bracket-wire combination was removed after performing each test and a new set was placed. The recorded data were analyzed using one-way analysis of variance (ANOVA). To determine the differences between the groups, Tamhane's T2 post hoc test was used due to the significant differences between the variances as analyzed by Levene's test (p<0.005). Statistical analysis was performed using SPSS statistical software (SPSS 22 for Windows; SPSS Inc., Chicago, IL, USA) at the 0.05 significance level. September 2017; Vol.14, No

4 J Dent (Tehran) Hosseinzadeh Nik et al Table 1. Specifications of the evaluated toothpastes Toothpaste Manufacturer Lot number Ingredients Expiry date Sorbitol, Aqua, Hydrated Silica, PEG-12, Sodium Lauryl Sulfate, Aroma, Cellulose Gum, Tetrasodium Pyrophosphate, Cocamidopropyl Colgate Total Colgate-Palmolive Betaine, Sodium Fluoride, Sodium Saccharin, Advanced 4340 Co., Ltd., China Hydroxypropyl Methylcellulose, Glycerin, Whitening Limonene, CI 74160, CI 74260, CI 77891, Sodium Fluoride 0.32% w/w (1450ppmF ). Colgate Total Pro Gum Health Colgate-Palmolive, Co., Ltd., China 5093 Sodium Fluoride 0.32% (1450ppmF ), Triclosan 0.30%, Aqua, Hydrated Silica, Glycerin, Sorbitol, Sodium Lauryl Sulfate, PVM/MA Copolymer, Aroma, Cellulose Gum, Sodium Hydroxide, Propylene Glycol, Carrageenan, Sodium Saccharin, Limonene, CI Colgate Anticavity Colgate-Palmolive Co., Ltd., China 6050 Sodium Monofluorophosphate 0.76% (0.15% w/v fluoride ion), Dicalcium Phosphate Dihydrate, Water, Glycerin, Sodium Lauryl Sulfate, Cellulose Gum, Flavor, Tetrasodium Pyrophosphate, Sodium Saccharin Ortho.Kin KIN Corp., Spain 15B05 GUM Ortho Sunstar Co., Spain J25 Aqua, Sorbitol, Hydrated Silica, Glycerin, Titanium Dioxide, Aroma, Cocamidopropyl Betaine, Panthenol, Xylitol, Xanthan Gum, Peg- 40, Hydrogenated Castor Oil, Sodium Fluoride, Sodium Methylparaben, Sodium Saccharin, Tocopheryl Acetate, Sodium Propylparaben, Cetylpyridinium Chloride. Aqua, Sorbitol, Hydrated Silica, Isomalt, Peg-8, Lauryl Glucoside, Aroma, Xanthan Gum, Cocamidopropyl Betaine, Panthenol, Sodium Saccharin, Sodium Fluoride, Allantoin, Sodium Methylparaben, Tocopheryl Acetate, Bisabolol, Zingiber Officinale Root Extract, Cetylpyridinium Chloride, Aloe Barbadensis Leaf Juice, CI 47005, CI 42090, Potassium Sorbate, Sodium Benzoate, Limonene RESULTS Table 2 shows the descriptive data of the frictional resistance values of stainless steel brackets and wires in the experimental and control groups after brushing. The maximum frictional resistance value was related to Colgate Total Pro Gum Health toothpaste. The frictional resistance values related to Ortho.Kin, GUM Ortho and Colgate Total Advanced Whitening toothpastes were not significantly different from that of the control group (P>0.22). However, there was a significant difference in the frictional resistance between Colgate Total Pro Gum Health and Colgate Anticavity toothpastes with that of the control group (P=0.004 and 0.001, respectively). DISCUSSION Determining the precise amount of the friction produced during orthodontic treatment is difficult due to the diversity of the influencing factors. Several factors may directly or indirectly influence the friction between the wire and bracket such as the alloy type, shape and diameter of orthodontic wires, type of ligation, manufacturing method (sintering vs. casting) and biological factors including saliva and acquired pellicle and plaque [16] September 2017; Vol.14, No. 5

5 Hosseinzadeh Nik et al Frictional Resistance of Orthodontic Brackets and Wires by Toothpastes Table 2. The frictional resistance values (N/mm2) between the stainless steel wires and brackets in the experimental and control groups Groups Number Minimum Maximum Mean Std. Deviation P-value* Control Colgate Total Advanced Whitening Ortho.Kin GUM Ortho Colgate Total Pro Gum Health Colgate Anticavity *Compared with the control group The effect of different types of toothpaste on the frictional resistance between orthodontic metal brackets and archwires has not been previously studied. In the present study, the effect of different types of toothpaste on the frictional resistance between orthodontic stainless steel brackets and archwires was investigated. The static friction was assessed in this study because it has been considered to be more important than the kinetic friction. The sliding motion of the teeth along an archwire occurs in a series of short steps instead of a continuous movement. Thus, the static friction must be overcome each time the teeth move [17]. In the present study, the ligation method between the bracket and wire was standardized to eliminate the effect of this variable, since the ligation system is one of the variables influencing the frictional force [18]. The results of this study showed that the frictional resistance values related to the orthodontic toothpastes (Ortho.Kin and GUM Ortho) were similar to that of the control group. The common material used in both GUM Ortho and Ortho.Kin toothpastes is cetylpyridinium chloride (CPC). This ingredient might have been responsible for the decreased frictional resistance of these groups. On the other hand, the highest amount of frictional resistance was related to Colgate Total Pro Gum Health toothpaste. This might be due to the presence of Triclosan active component in this toothpaste. However, it should be noted that we did not find supporting data in the literature to confirm the above conclusions and thus, further studies are required in this regard. It should be noted that the mean frictional resistance value related to Colgate Total Advanced Whitening toothpaste was higher than those related to the orthodontic toothpastes and control group even though the difference in the friction between these groups was not significant. Several studies have evaluated the abrasive effect of toothpastes on the enamel. Moghareh-Abed et al [19] and Yaghini et al [20] have investigated the effect of different commercial toothpastes on enamel abrasion. They concluded that there were no significant differences in the enamel abrasion between the evaluated toothpastes. Furthermore, contradictory information exists about the relationship between the friction and surface roughness. Nishio et al [18] reported that the stainless steel wire with the smoothest surface demonstrated the minimum frictional force value. Saunders and Kusy [21] have shown that the archwire alloy might have a more prominent impact on the frictional characteristics than the bracket type and surface roughness. In addition, Prososki et al [22] and Doshi and Bhad-Patil [23] found no relation between wire roughness and frictional resistance. In the present study, the frictional resistance values related to Colgate Total Advanced Whitening, Colgate Total Pro Gum Health, and Colgate Anticavity toothpastes were approximately similar and higher than that of the control group. Therefore, if a correlation exists between the friction and surface roughness, our September 2017; Vol.14, No

6 J Dent (Tehran) results would be coordinated with those of other related studies in which no significant difference was observed in enamel abrasion between the evaluated toothpastes [19,20]. Also, the fluoride contents of the evaluated toothpastes were approximately equal (1450 part per million (ppm) fluoride except for GUM Ortho with 1490 ppm). Therefore, it may be concluded that fluoride does not have a significant effect on the frictional resistance. Finally, it should be noted that several intraoral variables such as saliva, plaque, chewing force, bone density, tooth number, anatomic configuration, and occlusion can influence the frictional force levels. These factors were not evaluated in the present study; therefore, the frictional forces reported in the current study might be different from the actual forces exerted during orthodontic movements [5]. Further clinical studies are required to investigate the effect of different types of toothpaste on other types of archwires and also on the friction during orthodontic treatments. CONCLUSION According to the results, orthodontic toothpastes did not increase the frictional resistance between the orthodontic stainless steel brackets and wires and can be recommended to patients during orthodontic treatments. ACKNOWLEGEMENTS This research was accomplished as a professional thesis in Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences (thesis No: 879). The authors would like to thank Dr Mohammad Javad Kharazi Fard for his contribution in performing the statistical analysis of this study. REFERENCES 1- Khoury ES, Abboud M, Bassil-Nassif N, Bouserhal J. Effect of a two-year fluoride decay protection protocol on titanium brackets. Int Orthod Dec;9(4): Hosseinzadeh Nik et al 2- Huang HH. Variation in surface topography of different NiTi orthodontic archwires in various commercial fluoride-containing environments. Dent Mater Jan;23(1): White DJ, Schneiderman E, Colón E, St John S. A profilometry-based dentifrice abrasion method for V8 brushing machines. Part I: Introduction to RDA-PE. J Clin Dent. 2015;26(1): Brandão GA, Simas RM, de Almeida LM, da Silva JM, Meneghim Mde C, Pereira AC, et al. Evaluation of ionic degradation and slot corrosion of metallic brackets by the action of different dentifrices. Dental Press J Orthod Jan-Feb;18(1): Hosseinzadeh Nik T, Hooshmand T, Farazdaghi H, Mehrabi A, Razavi ES. Effect of chlorhexidinecontaining prophylactic agent on the surface characterization and frictional resistance between orthodontic brackets and archwires: an in vitro study. Prog Orthod Nov;14(1): Bednar JR, Gruendeman GW, Sandrik JL. A comparative study of frictional forces between orthodontic brackets and archwires. Am J Orthod Dentofacial Orthop Dec;100(6): Ho KS, West VC. Frictional resistance between edgewise brackets and archwires. Aust Orthod J Oct;12(2): Vaughan JL, Duncanson MG Jr, Nanda RS, Currier GF. Relative kinetic frictional forces between sintered stainless steel brackets and orthodontic wires. Am J Orthod Dentofacial Orthop Jan;107(1): Kao CT, Ding SJ, Wang CK, He H, Chou MY, Huang TH. Comparison of frictional resistance after immersion of metal brackets and orthodontic wires in a fluoridecontaining prophylactic agent. Am J Orthod Dentofacial Orthop Nov;130(5):568.e Kao CT, Guo JU, Huang TH. Comparison of friction force between corroded and noncorroded titanium nitride plating of metal brackets. Am J Orthod Dentofacial Orthop May;139(5): Iijima M, Yuasa T, Endo K, Muguruma T, Ohno H, Mizoguchi I. Corrosion behavior of ion implanted nickel-titanium orthodontic wire in fluoride mouth rinse solutions. Dent Mater J Jan;29(1): September 2017; Vol.14, No. 5

7 Hosseinzadeh Nik et al Frictional Resistance of Orthodontic Brackets and Wires by Toothpastes 12- Lee TH, Huang TK, Lin SY, Chen LK, Chou MY, Huang HH. Corrosion resistance of different nickeltitanium archwires in acidic fluoride-containing artificial saliva. Angle Orthod May;80(3): Kinoshita RYO, Sgura R, Reis MC, Masuda MS, Prazeres PSL, Júnior WR, et al. Effect of whitening dentifrices on surface roughness of dental nanofillerbased composites. Stereomicroscopy and AFM analysis. Braz Dent Sci Jul-Sep;19(3): Barbieri GM, Mota EG, Rodrigues-Junior SA, Burnett LH Jr. Effect of whitening dentifrices on the surface roughness of commercial composites. J Esthet Restor Dent Oct;23(5): ISO 11609:2017 (en). Dentistry-Dentifrices- Requirements, test methods and marking. Available at: 3:v1:en/ Publication date: June Alavi S, Farahi A. Effect of fluoride on friction between bracket and wire. Dent Res J (Isfahan) Dec;8(Suppl 1):S Frank CA, Nikolai RJ. A comparative study of frictional resistance between orthodontic bracket and arch wire. Am J Orthod Dec;78(6): Nishio C, da Motta AF, Elias CN, Mucha JN. In vitro evaluation of frictional forces between archwires and ceramic bracket. Am J Orthod Dentofacial Orthop Jan;125(1): Moghareh-Abed A, Izadi M, Kaveh M, Tavakoli M, Yaghini J. Comparative study investigating abrasive effects of 12 commercially available toothpastes on enamel, in Iran. J Mash Dent Sch. 2012; 36(3): Yaghini J, Izadi M, Moghareh-Abed A, Ebrahim H, Foroughi S. Comparing effects of four toothpaste types (Nasim, Crest 7, Crest Sensitivity and Daroghar3) on rate of enamel abrasion. J Shahid Sadoughi Univ Med Sci (JSSU), 2015 Mar-Apr;23(1): Saunders CR, Kusy RP. Surface topography and frictional characteristics of ceramic brackets. Am J Orthod Dentofacial Orthop Jul;106(1): Prososki RR, Bagby MD, Erickson LC. Static frictional force and surface roughness of nickeltitanium arch wires. Am J Orthod Dentofacial Orthop Oct;100(4): Doshi UH, Bhad-Patil WA. Static frictional force and surface roughness of various bracket and wire combinations. Am J Orthod Dentofacial Orthop Jan;139(1):74-9. September 2017; Vol.14, No